The present disclosure relates to downhole electric submersible pump assemblies. More particularly, the present disclosure relates to electric submersible pump assemblies configured to provide improved bending flexibility during installation in downhole deviated wells.
Electric submersible pump assemblies are used in a wide variety of environments, including wellbore applications for pumping production fluids, such as water or petroleum. Electric submersible pump assemblies typically include, among other components, a submersible pump that provides for the pumping of high volumes of fluid, such as for use in oil wells which produce large quantities of water, or high volume water wells and a submersible motor for operating the electric submersible pump. A typical electric submersible pump utilizes numerous stages of diffusers and impellers, referred to as pump stages, for pumping fluid to the surface from the well. During operation, the impellers are configured to rotate within the diffusers.
Recovery of hydrocarbon resources has led to the development of advanced drilling and completion strategies for wells in gas and oil reserves. Many of these wells deviate from a straight path in order to enter production zones and follow geological formations that are often within a narrow band. In many cases it is desirable to install artificial lifting equipment such as the previously described electric submersible pumps to produce fluids from deviated wells. Traditional equipment is designed to be somewhat rigid and typically accommodates only a small degree of bending.
In some cases the diameter of the well is selected to be larger than that necessary to achieve maximum production rates and to allow smaller diameter and more flexible equipment to be installed within. The cost of drilling larger diameter wells and installing larger well casing represents a significant capital expense that is negatively impacted. In other cases, wells are drilled with less severe bends, or lower values of “Dogleg Severity” (DLS), to accommodate traditional electric submersible pumping equipment with only a limited degree of flexibility. This need to provide bend radii when drilling a well results in longer total lengths of wells or otherwise reduced coverage within a production zone.
In order to increase flexibility of electrical submersible pumps it is possible to design smaller and smaller diameter equipment. Such equipment will accommodate deviated wells with greater dogleg severity, but typically provide inferior performance compared to larger diameter equipment. It is known that a maximum production rate possible with reduced diameter equipment is less than a maximum achievable rate with larger diameter equipment.
Accordingly, it is desired to provide for an electric submersible pump assembly that provides for installation of equipment within wells that have a deviation from a straight path and therefore enables greater optimization of drilling strategies without requiring the use of reduced diameter equipment. Further it is desired to provide a flexible electric submersible pump assembly that allows increased production rates and greater total recovery from a reserve that is exploited using deviated wells.